基于正交频率脉冲编码激励的软组织粘弹性定量测量

发布时间：2018-09-17 17:58

【摘要】：高频剪切波对粘性参数的准确估计非常重要。为了提高高频剪切波的检测能力,并研究其对粘弹性参数估计的影响,本研究探讨了基于正交频率脉冲激励的超声振动计方法。通过构造具有特定频谱特性的正交频率波形,经稀疏采样之后激励组织振动,可以增强剪切波的高频分量。以新鲜猪肝为对象进行离体实验。选择二进制编码和两种正交频率编码脉冲激励组织振动,然后分别运用激光振动计和超声对不同编码激励方式产生的剪切波进行检测。激光振动计实验证明了该方法可以有效增强剪切波的高频分量,而从超声实验结果上看,与二进制编码激励方式的结果相比,当只用100~400 Hz剪切波速度拟合求解时,三码片与六码片的正交频率脉冲激励所估计得到的剪切弹性和剪切粘性的相对偏差分别为2.3%和4.1%,13.6%和11.5%;而当将所有频率剪切波速度用于拟合求解时,三码片与六码片的正交频率脉冲激励所估计得到的剪切弹性和剪切粘性的相对偏差分别为10.6%和3.5%,5.4%和11.8%。实验结果表明,正交频率编码激励方式可以降低激励峰值声强,并提高系统对高频剪切波的检测能力;另一方面,高频剪切波对粘弹性估计值具有影响,但其影响方式还不确定,需要进一步研究。
[Abstract]:High frequency shear wave is very important for accurate estimation of viscosity parameters. In order to improve the detection ability of high frequency shear wave and to study its influence on the estimation of viscoelastic parameters, an ultrasonic vibrator method based on orthogonal frequency pulse excitation is studied in this paper. The high frequency component of shear wave can be enhanced by constructing the orthogonal frequency waveform with special spectral characteristics, which excites the tissue vibration after sparse sampling. Fresh porcine liver was studied in vitro. Binary code and two orthogonal frequency coded pulses are selected to excite tissue vibration. Then the shearing waves generated by different coded excitation modes are detected by laser vibrometer and ultrasonic respectively. The experiment of laser vibrometer proves that this method can effectively enhance the high frequency component of shear wave. Compared with the results of binary coded excitation method, when the velocity fitting of shear wave is only 100 ~ 400 Hz, the method can be used to solve the problem. The relative deviations of shear elasticity and shear viscosity estimated by the orthogonal frequency pulse excitation of three and six codes are 2.3% and 4.1% 13.6% and 11.5%, respectively, and when all frequency shear wave velocities are used to fit the solution, the relative deviations of shear elasticity and shear viscosity are 2.3% and 4.1% and 11.5% respectively, and when all frequency shear wave velocities are used to fit the solution, The relative deviations of shear elasticity and shear viscosity obtained by the orthogonal frequency pulse excitation of three and six codes are 10.6% and 3.5% respectively. The experimental results show that the orthogonal frequency coded excitation method can reduce the peak sound intensity and improve the detection ability of the system to the high frequency shear wave, on the other hand, the high frequency shear wave has an effect on the viscoelastic estimation. But its influence mode is still uncertain, need further research.
【作者单位】：浙江大学生物医学工程与仪器科学学院;电子与计算机工程系圣克劳德州立大学;深圳大学医学院生物医学工程系;医学超声国家联合地方工程实验室;深圳大学医学院广东省生物医学信息检测与超声成像重点实验室;
【分类号】：R310

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